Updated: Jan 14
LADWP’s David Pettijohn guides the development of new water recycling infrastructure that will help ensure the reliability of future LA water supplies.
Whenever citizens of Los Angeles turn on a faucet, take a shower or flush a toilet, the resulting wastewater flows down a drainpipe into a local sewer system. From there it travels downhill through a network of sewer pipes to the Hyperion Water Reclamation Plant (HWRP) in Playa del Rey just south of LAX, where it is treated and released back into the ocean.
David Pettijohn, director of water resources for the Los Angeles Department of Water and Power (LADWP), thinks that’s the wrong outcome, particularly at a time when LADWP’s four million or so customers face increasingly unreliable supplies of fresh water exacerbated by climate change.
“Does it really make sense for us to import water from hundreds of miles away, use it one time, and then dump it into the Pacific Ocean?'” asks Pettijohn rhetorically.
Building a Sustainable Future
The answer to his question, of course, is an emphatic “no.” LADWP’s proposed solution is Operation NEXT, an initiative to recycle and reuse a large percentage of the treated wastewater from HWRP for the benefit of the City of Los Angeles, creating another sustainable source of fresh water for Los Angeles.
Operation NEXT will require the development of new water delivery infrastructure that includes an estimated 64 miles of pipelines, and more than a half dozen pumping stations and related storage and treatment facilities. LADWP hopes to complete the proposed infrastructure in next 20 to 30 years.
The agency is developing Operation NEXT in partnership with Los Angeles Sanitation and Environment which plans, through its own Hyperion 2035 program, to retrofit HWRP’s current conventional water treatment processes with advanced treatment processes. Those upgrades are expected to produce up to 217 million gallons per day of purified recycled water, or about 85% of the current average daily flow of wastewater treated at HWRP.
As director of water resources, Pettijohn concerns himself with two basic questions:
· Where is Los Angeles going to obtain its bulk water supplies? and
· What’s the best way to maintain the reliability of those supplies?
The city currently imports most of its drinking water from three sources: the Owens Valley in the Eastern Sierra Nevada Mountains via the Los Angeles Aqueduct system; the Sacramento-San Joaquin Delta via the State Water Project’s California Aqueduct; and the Colorado River via the Colorado River Aqueduct.
Unfortunately, observes Pettijohn, these sources are becoming less reliable and potentially more expensive, triggering the need for Operation NEXT, which he and his LADWP colleagues refer to figuratively as “the third Los Angeles Aqueduct.”
“Over the last 20 years, LADWP has experienced fairly steady declines in its water allocations from the State Water Project,” he advises. “And over the last 30+ years, we’ve seen a 50 percent reduction in historical flows from the Eastern Sierra Nevada to the Los Angeles Aqueduct.”
Faced with these water reductions, Pettijohn emphasizes, Operation NEXT becomes a critical tool in LADWP’s ability to meet its customers' the water needs.
The program will not be inexpensive to develop and implement, he admits, but those costs will be largely offset by water that the agency will no longer have to purchase on the wholesale market.
Pettijohn was born in Stuttgart, Germany, the son of a U.S. Army colonel trained as an engineer in extractive industries – think mining, quarrying, and oil and gas extraction. Like most military brats, he says, “I was raised a little bit of everywhere.”
His father’s service took the family from Germany to Urbana-Champaign, Illinois; to South Korea; to Fort Ord, Calif.; and eventually to Fort Huachuca, Ariz. near the town of Sierra Vista, where Pettijohn attended high school.
During these formative years, Pettijohn’s mailing address changed on a regular basis, but one thing never did: the work ethic of his family.
“My mom always talked about ‘stick-to-itiveness,’ being diligent and not quitting," he says. "She taught me that life is about persistence and perseverance in the face of difficulties and that you have to learn to weather the storm, and never give up.”
Engineering a Career
Fortunately, Pettijohn didn’t have to struggle with choosing a college major — engineering seemed like a logical fit — but it was perspective from his dad that really helped close the deal.
“I’d always been good at math and science,” he recalls, “but I knew I didn’t want to be inside all day. My dad said, ‘okay, there are some engineering fields, such as civil engineering, where you can work outside. Whatever you design inside will have to be constructed outside. So you could work outside overseeing the work of construction crews building those things you designed.’
“Well, that appealed to me, and it’s what really drew me to civil engineering," Pettijohn observes.
He completed his bachelor’s degree in 1980 and a master’s degree in 1982, both in civil engineering, both from the University of Arizona, Tucson.
Discovering Water and Power
Pettijohn’s degree initially took him to Los Angeles to work for Exxon, but after two years, he opted for opportunities with LADWP. For the next 10 years, he supported the agency's work designing and constructing power system dams and related hydropower projects in the Owens Valley.
When California deregulated its electric industry in the 1990s, however, forcing LADWP to compete with other electricity providers, Pettijohn transferred to the agency’s Water System. A few years later, he was offered a job in LADWP’s Water Resources Division where he’s worked ever since.
Sticking with Groundwater
For Pettijohn, one of the main engineering challenges for Operation NEXT is gravity.
“The Hyperion Wastewater Reclamation Plant sits at the bottom of our gravity flow system,” he points out. “So, we’re going to have to build a pipeline network and a pumping system to deliver advanced treated water up to the Los Angeles Aqueduct Filtration Plant (LAAFP) in Sylmar. From there we can deliver potable water to about 70 percent of our service territory.”
Pumping water a long distance, however, is very energy intensive, Pettijohn adds. So LADWP plans to use some of the advanced treated water from HWRP to recharge local aquifers instead.
This method involves injecting water into one of the agency’s three LA-area groundwater spreading basins — large, flat areas of porous, sandy soil — and allowing it to percolate down to the groundwater table, a process that filters and further purifies the water.
Fortunately, advises Pettijohn, the water delivery infrastructure required to convey water from HWRP to LADWP’s spreading basins or the LAAFP all constitute mature, off-the-shelf technology.
“Injecting water into groundwater basins, spreading water in groundwater basins, extracting water from groundwater basins and treating water, that's really our bread-and-butter work,” he says.
The work on Operation NEXT will have to wait a while, however, as the program — it is slated for completion within the next two to three decades — is currently undergoing its key environmental review under the California Environmental Quality Act. That review is expected to be complete by 2023.
Rising Early, Pushing Hard
Workdays begin early in the home that Pettijohn shares in Porter Ranch, Calif. with his wife, two boys and two English bulldogs — Little Sister and Boomer. He’s usually up by 4:30 a.m., out the door by 5:00 and in his office in downtown Los Angeles – about 30 minutes by car from Porter Ranch — by 5:30.
These days, Pettijohn is in the office most days, preferring face-to-face interactions with his team over Zoom calls. A typical day includes meetings, phone calls, work product reviews, and strategic planning with senior LADWP management. Sadly, his opportunities to visit or inspect LADWP job sites have become far too infrequent.
Improving Lives with Water Delivery Infrastructure
In the end, Pettijohn thrives on guiding the development of what’s being billed as a “drought-proof” water supply, a system that may one day meet up to one third of LA’s water requirements. And he’s not afraid to think about Operation NEXT in bolder, more historical terms.
“We’re really engineering a civilization,” he suggests. “Whether we’re paving roads or installing a water delivery infrastructure, we’re improving the lives of millions of residents of the City of Los Angeles. We’re a small but important part of the human experience. What we build will outlive us all and continue to benefit millions of lives after we’re gone.”
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If you enjoyed this post, I encourage you to read my profile of John Bednarski and his team at the Metropolitan Water District of SoCal who are turning treated wastewater into ultra-pure drinking water for Southern California.